Homozygotes manifest fatal thromboses in the neonatal period—massive subcutaneous thrombosis (neonatal
purpura fulminans) with cutaneous necrosis, gangrene, and widespread venous thrombosis, which usually starts
in the first 24 hours of life. Severe bilateral vitreous hemorrhages,
gangrene, and widespread venous thrombosis have been reported. Bilateral
adrenal hemorrhage may lead to abdominal pain, hypotension, and
hyponatremia. Hypertension and congestive cardiac failure commonly result
from renal involvement. Treatment with heparin, antiplatelet drugs, or both
is not effective. The only successful treatment is protein C replacement
using protein C human concentrate, fresh-frozen plasma, or factor IX
concentrate.